Electric metal-working apparatus.



No. 666,l6|. Patented Ian. I5, I901.

\E. THOMSON.

ELECTRIC METAL WORKING APPARATUS.

' Application filed July 3, 1899.\

(No Model.)

UNITED STATES PATENT OFFICE.

ELll-IU THOMSON, OF SWAMPSCOTT, MASSACHUSETTS, ASSIGNOR TO THE THOMSONELECTRIC XVELDING COMPANY, OF LYNN, MASSACHUSETTS.

ELECTRIC METAL-WORKING APPARATUS.

SPECIFICATION forming part of Letters Patent No. 666,161. dated January15, 1901.

Application filed July 3, 1899. Serial No. 722,846] No model.)

To (LZZ witont it may concern.-

Beit known that l, ELIHU THOMSON, a citizen of the United States, and aresident of Swampscott, in the county of Essex and State ofl\lassachusetts,have invented a certain new and useful ElectriclVIetal-VVox-king Apparatus, of which the following is a specification.

My present invention relates to means for operating and controllingelectric welding or other electric metal-Working apparatus from adirect-current supply; and it consists of thefollowinginstrumentalities,combined and operating as hereinafter setforth: first, a transformer with an open magnetic circuit such as isprovided by astraight magnetic core whose ends are free, around whichcore is a primary coil in close inductive relation to the heavy coarsesecondary to which clamps for holding the work are attached; second, aninterrupter of the tVehnelt typethat is, a metal anode of limitedsurface immersed in an electrolyte opposite which is a cathode of metalof more extended surface, and, third, any suitable source ofdirect-currentsupply from which current may be passed through theinterrupter and primary coil of the said transformer,suiI-able control-switches being associated with the apparatus for putting on andcutting off the current at will.

It is to be understood that other forms of interrupter seen ring rapidbut absolute breaks in the circuit may be employed instead of thatalluded to. Vhatever form of interrupter be employed, however, thereshould be no resistance or condenser placed in shunt around the point ofinterruption, as such device, while it may diminish the sparking at thecontact only, does so by means of lessening the total eiifect andprevents the device operating to produce an absolute break when runningat high speeds, such as ordinarily exist in devices of this character.

Referring to the drawings, Figure 1 is a general plan of the apparatusand the connections; Fig. 2, a detail of the anode and interrupter, andFig. 3 a modification of Fig. 1. It is to be understood that the primarycoils and secondary coils, while shown adjacent to each other on thecore, may besuperposed or wound one above the other, and this issometimes the preferable construction.

1 I is an open magnetic-circuit core upon which are wound the coils P Por primary coils. The reason for using an open magnetic-circuit core isthat a closed magneticcircuit core saturates with too few ampereturns,and it does not drop its magnetism promptly on the cessation of theexciting-current, but retains a large proportion of the magnetism. Ifthe iron core be worked near saturation, the lossesare much greater thanif the core be an open core working below saturation.

Put in circuit through the interrupter B, which is shown as seated in aleaden bottle or casing C, with an opening in the side for the receptionof the rubber cork K or other stopper, from which passes a porcelain orglass tube bearing a platinum point, is the anode F in an electrolyte.

The secondary coil S of the transformer is very coarse and heavy, andits terminals bear electric welding-clarnps or like device for utilizingvery heavy current at W, where the heating effects are produced by theelectric resistance of the portion of closed secondary circuitcomprising the section of metal or work indicated between the clamps, asusual in the art.

D is the switch which controls the closing and opening of the primarycircuit. The course or direction of the continuous current is shown bythe arrows.

The interrupter device when suitably proportioned gives very rapidinterruption of the primary circuit P P, the rapidity.of theinterruptions being controlled in large measure by the completion of thecircuit through the work at W. When the secondary circuit containing thework is open, the rate of interruption is low relatively; but when it iswell closed the rate rises very considerably,

the output increasing with the degree of closure of the secondarycircuit S.

Fig. 2 shows the rubber cork or stopper K, through which the glass orporcelain thimble T passes, bearing on its inner end the platinumelectrode F, to which is soldered or integrally united a conductor oflarge section, as at B, so as to conduct off any heat which may form atthe platinum anode F.

In Fig. 8 the iron core of the transformer is rounded, so as to form anearly-closed magnetic circuit, but a circuit so open as to drop itsmagnetism When the current is interrupted in the primary coils P P. Thesecondary coil is, as before, a very heavy coil of but few turns, themaximum section of material being employed. I are the working-clamps, asbefore.

The invention claimed is- 1. In an electric metal-Working apparatus, thecombination, substantially as described, of a transformer having an openmagneticcircuit core and heavy secondaryconnected to the Work-clamps, asource of continuous current,and a rapid absolutein terrnpter incl nded

